Tire structure



June a, 1954 s. BONMARTINII 2,680,464

TIRE smucrfias' Filed March 12. 1952 In vlfrrfpr Patented June 8, 1954 UNITED STATES PATET GFFICE TIRE STRUCTURE Giovanni Bonmartini, Rome, Italy, assignor to Est Etablissement Sciences Techniques, Vaduz, Liechtenstein Application March 12, 1952, Serial No. 276,114

Claims priority, application Italy February 23, 1952 4 Claims. (01. 152-356) 1 2 The present invention relates to an improvetyre, with some parts removed in order to show ment in the structure of tyres for road wheels of the reinforcement of the tyre; vehicles and the like. Fig. 3 is a view like that of Fig. 2, wherein a The behaviour of the pneumatic tyres under second form of embodiment of the structure of the work load and in their practical conditions the reinforcement is shown; of use has been widely studied, in view of dimin- Fig. 4 is a sectional view taken along the symishing the wear of the tyre (particularly the wear metry plane of the tyre, perpendicular to the of tread), which occurs owing to the repeated axis of the said tyre; deformations and the contact friction with the Fig. 5 is a sectional view taken along the line ground, to which the tyre is submitted. V-V of Fig. 4, and corresponds with the form Although the behaviour of the tyre is very of embodiment shown in Fig. 2. complex, the main causes of wear may be con- With reference to Figs. 1, 2, 4 and 5 of the sidered the following two: the external friction drawings, the tyre having roughly a C-shaped due to the relative displacements between tread cross-section, comprises on each side a bead I and ground, and the internal friction due to incorporating a tensile stress working ring 2, to deformations. The first and the second friction which are connected the cords 3, forming an arc cause direct and indirect damages to the strucbetween the opposite rings along lines lying in ture of the tyre, by the mechanical stress diplanes passing through the axis of the tyre. rectly acting and by the thermic stress indi- The cords 3 are incorporated in the shrunk rectly acting thereon, with the concomitant reportion 4 of the periphery of the tyre 5, and sult of diminishing and rendering at last danare connected between themselves by flexible but gerous the resistance of the tyre. substantially inextensible elements 6, forming The classic system is that of reinforcing the (particularly when the tyre contains an inflated tyre with actual fabrics or by crossing layers of air chamber) catenary bridges between the sucparallel filiform elements so as to allow transcessive arcs of cord 3. verse and radial deformations of the tyre imped- It is to be noted that the wordings tensile ing substantially its peripherical deformations. stress working rings, cords, and flexible but This system has (through a complex of elastic substantially inextensible elements are all reand non-elastic deformations of the heteroferred to filiform or cord-shaped or band-shaped geneous system rubber-fabric) the inconvenience elements made of material flexible but practithat the instantaneous area of contact with the round is deformed, owing to the variation of the surface of its elemental small areas, during the time when it rests on the ground during the rotation of the wheel, repeated friction causing a wear of the tread by abrasion.

Both this abrading friction with the ground, and the complex of the deformations occurring with a stress in the body of the tyre, relatively rigid and thick, determine the fatigue of the tyre and its heating, which, hardly compensated by ventilation, produces serious damages and a dangerous reduction of its resistance.

The abmding friction with the ground is for the rings 2, steel cable having a smaller crossduced, according t t present invention, Owing section for the cords 3 and cotton or polyamidic to the fact that the small areas of the contact resins (nylon) cords for the a s 6. surface between the ground and the tread re- Instead Of arranging the y rn 6 as shown in main substantially still during the time of con- Figs- 4 and 5, 30 as o nect, by every tact in the wheel rotation, this being obtained Y m 6, tWO points of two successive arcs 3 at by the structure which is described here below, the Same distance from the r 2 (measured with reference to the attached drawings, wherein: along the are 3 it is 0 po s b e, Within the Fig. 1 is a side elevation of a tyre embodied Scope of th pr t invention, t p a aid yarns according to the present invention; 6 as shown in Fig. 3, i. e. so that the trend of Fig. 2 is a. detail perspective view of the same with the consequence of a cally inextensible under the loads which are normally applied thereon during the operation of the tyre. The material suitable to form these reinforcement elements, can be any yarn of natural or artificial textile fibres, or any thread of artificial substances (resins) or also any type and quality of metal and of metal alloy. Nevertheless. although the choice of the material suitable to each case can be made by every skilled person in the field, here below is indicated by way of non-limitative example, the following diagram of materials for the reinforcement made of rings 2, of the cords 3 and of the threads 6; steel cable the yarns will be substantially helicoidal in respect of the substantially toroidal shape of the tyre.

On the periphery of the tyre, which constructively is embodied by incorporating the elements 3 and 6 in a layer having a substantially uniform thickness, which layer assumes, by vulcanization with the reinforcement, the undulated shape which is shown in the drawing (i. e. the layer 5 assumes, between the cords 3, a shape which may be called catenary, forming outwardly projecting undulations of the peripherical surface of the tyre) are applied preferably, within the scope of the present invention, thicker portions 1 which, acting as tread, remain individually still, resting on the ground, during'therotation f t Wheel, while the peripherical deformations are all substantially supported by'the shrunk zones 4 of the periphery of the tyre, which zones have the maximum elasticity to flcction'in the peripherical sense.

In the case of'Fig. 3, the yarns-t, having helicoidal trend and forming bridges between the successive arcs 3, are preferably arranged in an even number of layers, with opposite trend, as shown in 5, in order to give the symmetry of deformation to the shrinking portions l of the tyre,-'whenthey are deformed during the operation. However this crossed arrangement 5' is preferable but not-necessary, as layers of yarns 6, having all the same 'helicoidal trend, may be usefully employed.

Theyarns't are relatively thin and numerous, and arranged so' that the medium distance between two' adjacent yarns is of the same order or the'ra'dius of the yarn, so that when the pneumatic tyre is inflated, there is no tendency to ahernia-like-breakingof theelastic rubber, (or equivalent elastic material) placedbetween two yarns and connected to each yarn by vulcanization or other-equivalent system.

The structureor Fig. 3, with the crossed reinforcement 3- secured to the cords 3 has remarkable constructive"advantages, as it can be embodiedwith an art similar to that presently r01- lowed for the common tyres; said structure has furthermore technical advantages of use, as the crossed structure 6 -pra'ct'callybraces the tyre against the transverse stresses which, particularly when the vehicle, whereon the tyre is mounted, travels along a curve, can reach remarkable values.

According to the present invention, the'tyre can be completed in itsinternal part (corresponding to the interval between the two beads i of the illustrated forms of embodiment) so as to assume the shape of-a tube or of a-tubular tyre, in-which case, in-a known way, thesame tyre can'act as an air chamber. The embodiment can, then be simplified, and assume the shape shown in Figs. 1,2, 3, 4 and 5 of the U. S. patent application 150,666 dated March 20, 1950, or the shape illustratedinFigs.- 1 to 6 of Italian patent application filed at Rome on February 21, 1951, filing certi'ncate Record No. 48,No. 428both of Est Etabli'sseme'ntsciences Techniques. In the two aforecited'documents, the tubular tyre is indicated as destined to operate as a track on two or more grooved wheels, while in the present invention the same tubulartyre is mounted like acommon pneumatic tyre on a single grooved'wheel. In this case, during the *operation, the pneumatic tyre does not modify'its internal radius of curvature, and practically are concerned" only theexternalor periphericalparts of the undulations.

The greatersurface offered to the air by the 4 tyre according to the present invention and the same undulated shape, favour ventilation and cooling of the tyre, which also owing to this reason, tends to be heated far less than the ordinary tyres.

The present invention has been described and illustrated in some preferred forms of embodiment, but it is understood that constructive variations (for instance in the shape of tread) may be brought thereto, without issuing from the scope of this invention.

I claim:

1. Atirefor road wheels of vehicles comprising in combination a wall of elastic material pro-- 'vided-*along its outer surface with corrugations wherein the facing tranverse surfaces of successive'corrugations are spaced from each other, two beads in the inner part of said wall of elastic material for connection with the wheel, a circular substantially filiform, flexible and inextensible element in the shape of -a ring embodied in each of said beads, a plurality of flexible and inextensible arc-shaped transverse cords lying in transverse planes passing through the axis or the wheel and embodied in the wall of elastic material at the inner parts of the corrugations and connected at their ends to the said rings and perpendicular'to the latter, a plurality of flexible and inextensible threads crossing said transverse cords and disposed in-wave form.- with arcuate portions connecting two-by-two the transverse cords embodied :in the wall of elastic material at the inner parts of the corrugations.

2. Ina tire for road wheelsoi vehicles, a wall of elastic material provided with two beads for connection to the wheel and with an outer surface formed with'corrugations wherein the facing surfaces of two adjacent corrugations are spaced from each other, circular filiform, flexible and inextensible elements in the form of a ring embodied in the said beads, transverse flexible and inextensible cords'in the form of an'arc'embodiedin the wall of'elastic material at the inner part of the corrugations, said'tranverse cords being connected at their ends to said rings embodied in the beads and being adapted to keep the corrugated shape of the tire in all the'conditions of operation 'thereof,flexib1e and inextensible threads crossing saidtra'nsverse cords and disposedinwave form with arcuate portions connecting two-'by-two the transverse cords embodied'in the wall of elastic material at the inner parts of the corrugations.

'3. In a tubular tire forroad wheelsof vehicles, a wall of elastic material provided with twobeads for connection to the wheel and with an'outer ground contacting surface formed with corrugations wherein the facing transverse surfaces of two successive corrugations are spaced from each other, the said'wall or" elastic material having embodied therein a deformable structure'formed with two substantially filiform, flexible and inextensible rings embodied in said beads, aplurality of transverse arc-shaped cordsp-arallel to each other,"each of the said cords connected at the-ends to the said rings and embodied in the wall-at the inner part or the corrugations to keep the corrugatedshape of the outer surface of the wall in all the conditions ofbperation of the tire, a plurality of'fiexible and inextensible threads parallel to each other and crossing said transverse cords, said threads being waveform and having portions in the shape of arcs connecting two-by-two said transverse cords embodied-in the wall at the inner part of the corrugations, the

5 outer surface of the elastic wall being provided with tread at the outer part of the corrugations contacting the ground.

4. In a tubular tire for road Wheels of vehicles, a Wall of elastic material provided with two beads for connection to the wheel and with an outer contacting surface formed with corrugations wherein the facing transverse surfaces of two successive corrugations are spaced from each other, the said wall of elastic material having embodied therein a deformable structure formed with two substantially filiform, flexible and inextensible rings embodied in said beads, a plurality of transverse arc-shaped cordsparallel to each other, each of said cord connected at the ends 1 to said rings and embodied in the wall at the inner part of the corrugation to keep the corrugated shape of the outer surface of the wall in all the conditions of operation of the tire, a plurality of flexible and inextensible threads arranged in crossed layers, said layers being waveform with portions in the shape of arcs connecting two-bytwo the said transverse cords embodied in the Wall at the inner part of the corrugations, the outer surface of the elastic wall being provided with tread at the outer part of the corrugations 10 contacting the ground.

References Cited in the file of this patent UNITED STATES PATENTS 

